We have found that the cuticle of the nematode Caenorhabditis elegans contains a large number of different collagen proteins and that the structure and composition of the various juvenile stage cuticles differ from each other and from the adult. Over 30 genes hve been identified that affect cuticle structure and some of these are stage specific. We plan to use stage specific cuticle mutants to identify major regulatory genes that control the transitions between developmental stages. We will use monoclonal antibodies and lectins to further characterize the cuticle proteins and to aid in identifying the nature of the defects in cuticle mutants. Cuticle mRNAs will be characterized by in vitro translation and restriction mapping of cDNAs to determine the number of collagen genes involved in cuticle formation. We will use cloned cDNA fragments containing collagen-coding sequences to follow development to determine the molecular basis of the regulation of cuticle formation and the role of regulatory genes in this process. Many nematodes are plant or animal parasites. They are major agricultural pests and health hazards in many areas of the world. This work will increase our understanding of nematode biology and thus possibly lead to more effective nematode control both in agriculture and medicine. Collagens are major components of connective tissue and affected in many diseases. Our studies may help to elucidate the evolutionary origins of collagens and the molecular mechanisms involved in their formation. Little is known about the genetic control of development. Our study of regulatory genes controlling stage transitions in the nematode may contribute significantly to this poorly understood area of biology.